Lagoons and Land Disposal Systems

Since food wastes contain suspended and soluble organic contaminants, they are readily treated in lagoons and land disposal systems. The lagoons may be complete storage ponds, frequently used by seasonal processors for waste containment. In four to six months, the waste is stabilized, with up to 90% BOD reduction. If large lagoon acreage is available, aerobic conditions are maintained by limiting organic loadings to less than 100 lb of BOD per acre per day. When extremely strong wastes are encountered, a combination of anaerobic and aerobic lagoons provides an excellent means of treatment on less land, since the anaerobic system may reduce BOD from 60% to 90%, reducing the aerobic lagoon acreage required to achieve desired effluent quality.

Anaerobic lagoons are odorous and require an artificial or natural cover. In meat products, the high grease content forms a natural cover. Aerobic lagoons can also cause odors if overloaded and lacking sufficient dissolved oxygen. Various mechanical aeration methods have reduced required lagoon acreage, but these increase power costs.

Land disposal can be achieved by flooding; however, the most efficient means is conventional farm spray irrigation equipment. Sandy soil with a high infiltration rate offers no surface runoff, and no discharge to a receiving stream. Recently, an overland flow technique has been developed as an equivalent of tertiary treatment.

FIG. 8.2.6 Wastewater treatment maze (for organic waste from food processing industries). The diagram illustrates the many options open to solving waste treatment problems. The best route through the maze is suggested by an engineering study and report. Such a report discloses possible treatment methods, anticipated influent properties, effluent requirements and costs. Most important, the report serves as a mutually agreed-upon criterion with regulatory agencies. Designing a waste treatment system should not be considered without such a study and report.

FIG. 8.2.6 Wastewater treatment maze (for organic waste from food processing industries). The diagram illustrates the many options open to solving waste treatment problems. The best route through the maze is suggested by an engineering study and report. Such a report discloses possible treatment methods, anticipated influent properties, effluent requirements and costs. Most important, the report serves as a mutually agreed-upon criterion with regulatory agencies. Designing a waste treatment system should not be considered without such a study and report.

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